1. Field of the Invention
The present invention relates to a revolving construction machine such as a hydraulic excavator, for example, and more particularly to a revolving construction machine being able to swing with a small swing radius.
2. Description of the Related Art
Generally, hydraulic excavators and so on are known as revolving construction machines. A hydraulic excavator is made up of a lower track structure, an upper revolving structure rotatably mounted on the lower track structure, and a working device attached to a front portion of the upper revolving structure.
The upper revolving structure is mainly constructed of a revolving frame having a skeleton structure, a counterweight disposed on a rear portion of the revolving frame to balance with the working device, an engine cover positioned in front of the counterweight to cover an engine mounted on the revolving frame, a floor panel positioned in front of the engine cover to cover an upper surface of the revolving frame, and an operator's seat positioned in front of the engine cover and mounted on the floor panel. The working device is mounted to a front portion of the revolving frame.
Hydraulic excavators include revolving hydraulic excavators called the tail end small swing radius type and the minimal swing radius type (hereinafter referred to simply as small swing radius type hydraulic excavators). The small swing radius type hydraulic excavator is constructed such that when viewed from above, at least a portion of the upper revolving structure where the counterweight is positioned is substantially circular with respect to the center of rotation of the upper revolving structure, and when the upper revolving structure swings, at least the side of the counterweight is kept substantially within the track structure width. With that construction, the counterweight portion for which the operator has poor visibility from the operator's seat is able to swing substantially within the track structure width, and safety in work is ensured. According to descriptions, hydraulic excavators wherein a rear portion of an upper revolving structure projects beyond the track structure width until about 20% thereof, can be regarded as falling in the category of the tail end small swing radius type and the minimal swing radius type. Also, as for the term "within the track structure width", even if an upper revolving structure of a practical hydraulic excavator projects beyond the track structure width to some extent, such an upper revolving structure is also regarded as being substantially within the track structure width.